Radio-frequency identifier (RFID) methods are widely used in a number of applications, including smart cards, item tracking in manufacturing, inventory management in retail, etc. An RFID tag can be attached, e.g., to an inventory item. An EIR terminal can be configured to read the memory of an RFID tag attached to an inventory item.
EIR terminals with integrated RFID reading capabilities can read RFID tags from a range of distances and various terminal orientations with respect to an RFID tag being read. When an EIR terminal comprising an RFID reader is configured to display a scan trace, it provides the EIR terminal's operator with a visual feedback with respect to the scanning progress. At any moment in time, the RF signal coverage emitted by an EIR terminal can be defined by a 3D shape. The form and size of the 3D shape defining the RF signal coverage depends, among other factors, on the orientation of the EIR terminal, the RFID transmit power level, and the number and configuration of the RF antennas employed by the EIR terminal. Hence, a target scan area by an EIR terminal can be visualized as a projection of the 3D RF signal coverage shape onto an arbitrarily chosen plane.
For a moving EIR terminal, a visual scan trace can be provided by different graphical representations such as a solid line, continuous line, or a dotted line, each line defined by a multitude of time varying points, each point being a projection of the 3D RF signal coverage shape onto the arbitrarily chosen plane at a given moment in time. The imaginary plane onto which the visual scan trace is projected can be chosen to intersect a physical structure containing a plurality of items to be inventoried, and thus the scan trace can be overlaid over an image of the physical structure.
RFID readers usually offer improved efficiency over bar code scanning devices for retail inventory, by being capable of reading multiple RFID tags that are within range of the RF signal transmitted by an RFID reader. A downside to this multiple-read capability is lack of scanned items localization, due to insufficient correlation between where the RFID reader is located or oriented, and the RFID tags being read. Retail inventory management typically requires more than 90% of the RFID tags present in a department to be successfully acquired during the inventory process. When this high accuracy is not achieved, it is currently necessary to rescan the entire department, since the locations of any unread RFID tags are unknown.
When items are scanned using an RFID reader, the antenna of this device transmits a signal. The longevity of use of an EIR terminal with an RFID reader is impacted by the transmit power level utilized in scanning RFID tags. The distance at which an RFID tag may be read by an RFID reader is proportional to the transmit power level emitted by the RFID reader. Thus, an RFID reader using a higher transmit power level than required may have the unintended effect of unintentionally scanning RFID tags that are proximate to the tags that the user desires to scan.
A need exists for a method and system for reading RFID tags that conserves the power of the device and increases the accuracy when scanning select RFID tags.
SUMMARY OF INVENTION
An object of the present invention is to increase profits by efficiently and effectively tracking inventory so that sales are not lost because items are unexpectedly out of stock due to inventory errors. When merchants do not purchase popular products under the mistaken impression that these products are still in stock, potential sales are lost.
Another object of the present invention is to simplify the effort required to track inventory.
Another object of the present invention is to extend the battery life of an EIR terminal by increasing the efficiency of the power utilized by an integrated RFID reader.
Another object of the present invention is to increase the accuracy of an RFID reader by selecting a power level based upon the distance of the RFID tags that will be scanned.
Another object of the present invention is to maximize the number of desired RFID tags read a given point in time by an RFID reader.
Another object of the present invention is to minimize the coverage on a physical structure of a transmitted RFID signal to better determine the scan path of an RFID reader in an EIR terminal.
Another object of the present invention is to better focus the RFID transmission to avoid reading RFID tags on adjacent physical structures.
An embodiment of the present invention includes the following components: 1) an EIR terminal configured to read RFID tags; 2) an EIR terminal configured to enable control of the RFID reader transmit power level, and 3) data regarding the overall dimensions of a physical structure for which a scan trace is to be displayed and the coordinates of an initial reference point on this physical structure.
In embodiments of the present invention, the dimension data for a given physical structure can be stored in at least one database, or it can be available as part of a custom bar code and/or RFID tag affixed to the physical structure. In an embodiment of the present invention, when the dimension data is stored in one or more databases, it is indexed by a value in a custom bar code and/or RFID tag affixed to the physical structure and accessed by the EIR terminal upon scanning this value.
An embodiment of the present invention utilizes an EIR terminal with a graphical user interface (GUI). This EIR terminal is configured to scan/read RFID tags and images of decodable indicia, such as barcodes. The ER terminal is augmented with an imaging device, positioning package, including but not limited to, a 3-axis (3 dimensional) accelerometer package, and a 9-DOF (degree of freedom) IMU (Inertial Measurement Unit) containing a 3-axis accelerometer, a 3-axis magnetometer, and 3-axis gyroscope sensors, to acquire movement and position calibration data regarding the motion of the EIR terminal. The mechanism to scan bar codes includes but is not limited to optical scanners and/or image capture devices, such as cameras.
In addition to the 3D accelerometer suite, in an embodiment of the present invention, a 3-axis magnetometer is integrated into an ER terminal. The magnetometer, which acts in part as a compass, is integrated into the software of the EIR terminal and executed on a processor in the EIR terminal. In another embodiment of the present invention, the magnetometer is integrated as a hardware component. The magnetometer tracks the movement of the EIR terminal, in three dimensions, through space by collecting data regarding the changes in the magnetic field around the ER terminal. Thus, together with the accelerometer package, the magnetometer is also involved in determining both the motion and the orientation of the ER terminal.
A 3-axis gyroscope sensor is integrated into an embodiment of the present invention. The gyroscope aids the 3D accelerometer in determining motion and orientation because the gyroscope allows the calculation of orientation and rotation. This addition of the gyroscope sensor provides a more accurate recognition of movement within a 3D space than the lone accelerometer package.
An embodiment of the present invention employs an integrated 3-axis accelerometer suite, 3-axis magnetometer, and a 3-axis gyroscope sensor. Together, these components provide data regarding the location of the EIR terminal while moving through space.
In another embodiment of the present invention, an integrated 3-axis accelerometer suite, 3-axis magnetometer, and a 3-axis gyroscope sensor are employed to provide data regarding both the location and the orientation of the EIR terminal as it moves through space.
An embodiment of the present invention utilizes a custom bar coding scheme for physical structures. Each custom bar code is encoded with data that describes the physical structure (e.g., display and/or storage mechanism) used to display and/or store inventory, including but not limited to a reference identifier, the dimensions of the physical space, number of shelves, display surfaces, and/or hanging racks on each physical structure.
An embodiment of the present invention utilizes an RFID-tagging scheme for physical structures. In this embodiment, each custom RFID tag contains data that describes the physical structure (e.g., display and/or storage mechanism) used to display and/or store inventory, including but not limited to a reference identifier, the dimensions of the physical space, number of shelves, display surfaces, and/or hanging racks on each physical structure.
As aforementioned, data describing the physical structure encoded in either a custom bar code and/or on an RFID tag may provide the full dimensional data for a physical structure, or may provide a reference that can be used by the EIR terminal via a communication connection to obtain the full information from a data source. In an embodiment of the present invention that utilizes a database or group of databases, including but not limited to one or more remote databases or one or more local databases, to retrieve the dimensions of a given physical structure, the records stored in the one or more databases are indexed by the decoded values of images of decodable indicia scanned by a bar code reader and/or signals from an RFID receiver/reader in the EIR terminal.
In an embodiment of the present invention, the bar code scanning capability of the EIR terminal and/or the RFID reading capability of the EIR terminal is utilized to scan a custom bar code or RFID tag affixed to the physical structure. The EIR terminal, upon decoding the data in the bar code and/or reading the data on the RFID tag, queries a database to obtain additional information about the physical structure that the encoded data represents.
In an embodiment of the present invention, a “scan and tap” method is utilized to map the location of at least one object in three dimensional space, relative to an initial point in three dimensional space. When an EIR terminal scans a signal of decodable indicia, such as a bar code or RFID tag, this EIR terminal reads the coordinates of the signal source in the local reference frame. By tapping the EIR terminal, the resultant spike in the accelerometer data is used to set the initial point coordinates (x0, y0, z0) and store these coordinates in a memory, including but not limited to, a memory resource in the EIR terminal itself, or an external resource accessible to the EIR terminal via a communications connection. In the reference frame of the EIR terminal, the coordinates are set to (0,0,0). Thus, as the EIR terminal moves through three-dimensional space, motion with respect to the EIR terminal's own (0,0,0) can be mapped to the local reference frame using the initial point coordinates (x0, y0, z0). In an embodiment of the present invention, the local reference frame is aligned with respect to the physical structure.
In another embodiment of the present invention, the EIR terminal integrated with an IMU (containing a 3-axis accelerometer, a 3-axis magnetometer, and 3-axis gyroscope sensors) is utilized to record both the location of the EIR terminal in three dimensional space and record the initial point coordinates, the IMU also assists the EIR terminal in determining the orientation of the EIR terminal, both during the “tap” and as it moves through space. The orientation of the EIR terminal describes the position of the EIR terminal itself. For example, an EIR terminal can be at a given location, for example (x0,y0,z0) but the orientation of the EIR terminal at this location may vary. The EIR terminal may be held perfectly upright at this location and that is one orientation, but the EIR terminal may also be held at an angle relative to any direction in three dimensional space. This angle would represent a different orientation. In this embodiment, the “tap” and when the EIR terminal in moved relative to the initial point, both the location of the EIR terminal and the orientation of the terminal are stored in a resource, including but not limited to an internal resource in the EIR terminal and/or an external memory resource accessible to the EIR terminal via a communications connection.
In an embodiment of the present invention, the EIR terminal utilizes the motion-tracking data and the initial reference point that is established in the “scan and tap” process to determine the distance between the RFID reader's antenna and the physical display and any merchandise located on the physical display.
In an embodiment of the present invention, the EIR terminal utilizes the determined distance from the physical structure and/or the merchandise displayed on the physical structure to adjust the RFID transmit power level to the minimum necessary to scan RFID tags on the merchandise on the physical display.
In an embodiment of the present invention, the EIR terminal's RFID reader is utilized to locate a specific RFID tag and/or all RFID tags in a given vicinity.
In an embodiment of the present invention, the EIR terminal's RFID reader transmit power level is adjusted to the minimum power level necessary to read RFID tags on the merchandise of the physical display.
In an embodiment of the present invention, the RFID transmit power level is dynamically readjusted in response to external conditions, including but not limited to, the passage of a time interval, a change in the distance between the EIR terminal and the physical structure, and/or the number of RFID tags read and/or not read.
Although the present invention has been described in relation to utilizing motion-tracking data and an established initial point to determine the distance between an RFID antenna and a physical display and the merchandise on the display, many other variations and modifications will become apparent to those skilled in the art.